Signs that Mateen could have been gay emerged as far back as 2006 when he asked a male classmate out on a date.

At the time Mateen was said to be going to gay clubs and chatting up men.

Mateen's first wife, Sitora Yusufiy, 27, whom he met online in 2009 and married soon after, told Daily News his family think he murdered the 49 because he was in turmoil about who he really was - not because he was an Islamic extremist.

'When we had gotten married, he confessed to me about his past -- that was recent at that time - and that he very much enjoyed going to clubs and the nightlife,' Yusufiy said.

She had told the FBI that he was unstable, and that she didn't believe he was part of a terrorist group - despite him pledging allegiance to ISIS before the attack and the fundamentalists later claiming responsibility for it.

'The FBI asked her not to tell this to the American media,' he told the station.

Yusufiy has also said that Mateen 'beat her': 'After a few months he started to beat me. He was mentally unstable… he was obviously disturbed. I know he had a history of [taking] steroids.

Mateen made his attack on Pulse early Sunday morning - but that wasn't the first time he'd been to the club,The Orlando Sentinel reported.

Remarks that Mateen drank heavily conflict with his apparently strict adherence to his Muslim faith, including regular worship at a mosque in his home town of Port St. Lucie - where he was quiet and kept to himself.

And Kevin West, who was also a regular at Pulse, told the Los Angeles Times that Mateen has messaged him on gay dating app Jack'd several times in the year before the attack.

However, he said, he never actually met the man until the morning of the attack.